Hydroxylamines are used in wide industrial applications such as a raw material of a medical and agricultural chemical intermediate, a reducing agent, a treatment agent for surface of metal, a fiber treatment and dyeing. However, free hydroxylamine has extremely unstable characteristics, for instance, it is easily decomposed under the conditions of an existence of metal ions (particularly heavy metal ions), a high temperature or a high concentration. Consequently, a salt of hydroxylamine, which is comparatively stable, is manufactured and used in general.
However, hydroxylamine is suitable for many applications rather than a salt of hydroxylamine. In addition, in many cases, handling of a hydroxylamine aqueous solution at a high temperature or a high concentration is required. Accordingly, a trial to stabilize hydroxylamine under the conditions of a high temperature, a high concentration and metal impurities such as Fe getting mixed with has been carried out.
For instance, the patent document 1 (U.S. Pat. No. 5,808,150) describes a stabilizing method of adding diethylenetriamine-pentaacetic acid or triethylenetetramine-hexaacetic acid as a stabilizer into a solution containing hydroxylamine.
However, there is a problem in which a hydroxylamine solution that contains diethylenetriamine-pentaacetic acid or triethylenetetramine-hexaacetic acid as a stabilizer has an insufficient effect for suppressing a decomposition of hydroxylamine at a high temperature or a high concentration or in a case that metal impurities such as Fe got mixed with.
Patent Document 1: U.S. Pat. No. 5,808,150